1. Field of the Invention
The present invention relates to a PROM writer for writing data in a PROM and, more specifically, to a PROM writer capable of writing data in a PROM by a writing algorithm other than that stored therein without replacing a memory storing the system program of the PROM with another one in such a case when a new algorithm is provided by a device maker. The writing algorithm referred to herein is a high-speed writing algorithm specific to a specific large-capacity PROM.
2. Description of the Prior Art
A prior art relevant to the present invention is described in a magazine: "Electronics", OHM-sha, Ltd., pp. 945-947, September 1983.
"Quick Program" of Fujitsu Ltd., for example, is constituted so as to operate in the following manner.
(a) Data is written in an address A at a pulse of 1 ms, and then the data written in the address A is read immediately for verification.
(b) The procedure of (a) is repeated twenty times at the maximum until the data is written correctly in the address A.
(c) When the data is written correctly in the address A by the Nth cycle of the data writing procedure, additional data is written in the address A at a pulse of N ms.
(d) The steps (a) to (c) are repeated for all the addresses.
A conventional PROM writer will be described hereinafter with reference to FIG. 2 showing the constitution of the conventional PROM writer.
In FIG. 2, there are shown a CPU 1, memories 2 and 3, a bus 4 and a PROM 5. The CPU 1, the memories 2 and 3 and a bus 4 constitute a conventional PROM writer, which writes data in the PROM 5.
The CPU 1 gives commands through the bus 4 to the memories 2 and 3 and the PROM 5 for write/read control operation. A system program and a first writing algorithm are stored in the memory 2, while data to be written in the PROM 5 is stored in the memory 3.
In operation, the CPU 1 reads the system program and the first writing algorithm stored in the memory 2 through the bus 4 and writes the data stored in the memory 3 in the PROM 5. When the PROM writer of FIG. 2 is required to write data in the PROM 5 by a second writing algorithm different from the first writing algorithm stored in the memory 2 in contents, the system program needs to be replaced with a suitable one. Accordingly, it is impossible to write data simply in the PROM 5 by the second writing algorithm.